Federer, who owns a record 17 Grand Slam titles, says Saturday on his website that he will stop working with Annacone after 3½ years together.

Says Federer: "We felt like this was the best time and path for both of us."

The move comes only two days after Federer's latest surprising loss in a year filled with them: He was beaten 6-4, 6-7 (5), 6-3 in the third round of the Shanghai Masters by Gael Monfils, a former top-10 players now ranked 42nd and recently back from injury.

The defeat hurt the 32-year-old Federer's chances of qualifying for the season-ending ATP Tour Finals. He has spent more weeks ranked No. 1 than any man but is currently No. 7.